Histology-based blood leukocyte profiling reveals parallel Th2 and Th17 signatures in seasonal allergic rhinitis

BACKGROUND: Allergic rhinitis (AR), a common condition in the westernized world, is suggested to be more immunologically complex than the archetypical 'Th2' inflammation. New approaches are needed to decode this complexity.

AIMS/OBJECTIVES: In this study, we explored a novel histology-based analysis for circulating blood leukocyte profiling in 16 patients with seasonal AR outside and during the pollen season.

MATERIAL AND METHODS: Leukocytes were purified with minimal ex-vivo artefacts, embedded into agarose-paraffin pellets for immunohistochemistry-based immune cell profiling. Blood leukocyte mapping was performed.

RESULTS: Samples collected during the pollen season had statistically increased eosinophils, neutrophils, monocytes, and CD8+ T-lymphocytes compared to the off-season baseline. In contrast, no change was observed for CD20+ B-lymphocytes and CD3+ T-lymphocytes. Subclassification of CD4+ T-helper cells demonstrated a parallel and significant expansion of Th2 and Th17-cells during the pollen season, while Th1-cells remained unchanged. Whereas absolute basophils numbers were unaltered, the basophil markers GATA2 and CPA3 increased during the pollen season.

CONCLUSIONS AND SIGNIFICANCE: This study introduces a novel and applicable method for systemic immune cell screening and provides further evidence of complex and parallel Th2 and Th17-immune signatures in seasonal AR. It also forwards GATA2 and CPA3 as potential biomarkers for ongoing allergic inflammation.